// Maybe 函子
class Maybe {
  static of(value) {
    return new Maybe(value);
  }
  constructor(value) {
    this._value = value;
  }

  map(fn) {
    return this.isNothing() ? Maybe.of(null) : Maybe.of(fn(this._value));
  }

  isNothing() {
    return this._value === null || this._value === undefined;
  }
}
// let r = MayBe.of("Hello World").map((x) => x.toUpperCase());
// console.log(r);

// 处理null的情况
// let r = MayBe.of(null).map((x) => x.toUpperCase());
// console.log(r);

// 存在难以发现null在什么位置出现的问题
let r = Maybe.of("hello world")
  .map((x) => x.toUpperCase())
  .map((x) => null)
  .map((x) => x.split(" "));
console.log(r);
